xv6-riscv Source Code
Unknown
MIT's xv6, a small Unix-like teaching kernel for RISC-V used in 6.1810. Its file system layer implements a buffer cache, write-ahead logging, inodes, directories, and path lookup in a few hundred readable lines of C, ideal for tracing how a real file system works.
More resources on File Systems
Operating Systems: Three Easy Pieces
Chapter from the free OSTEP textbook by Remzi and Andrea Arpaci-Dusseau introducing the Unix file and directory interface: open, read, write, fsync, rename, stat, hard and symbolic links, and mounting. Readers understand how programs interact with persistent storage through system calls.
OSDev Wiki - File Systems
OSDev community wiki page surveying file system formats and design for hobby operating system developers. It links to detailed pages on FAT, ext2, ISO 9660 and others, describing on-disk layouts so readers can write drivers that read and write real disk images.
CS162: Operating Systems and Systems Programming
UC Berkeley's upper-division operating systems course, with lectures, projects and exams covering processes and threads, synchronization, CPU scheduling, virtual memory, file systems, I/O and networking. Students build kernel features in the Pintos teaching OS and understand how operating systems work internally.
Operating Systems: Three Easy Pieces
Learn concurrency in operating systems with this course from Remzi & Andrea Arpaci-Dusseau, based on "Operating Systems: Three Easy Pieces."
osdev.org
OSDev.org is a community-driven resource and wiki for operating system development. It offers tutorials, articles, and sample code on topics like kernels, bootloaders, memory management, drivers, and other low-level OS concepts, plus forums for discussion.